Internal mandrel for headers



L. F. KOELLNER INTERNAL MANDREL FOR HEADERS Filed March 21. 1924 4 Sheets-Sheet 1 IN vEH 702 L. F: /%e//ne[1 4, guide W HTTOJENEKS Dec. s, 1925.

L. F. KOELLNER INTERNAL MANDREL FOR HEADERS 4 Sheets-Sheet 2 Filed March 21. 1924 INVENT'O/E L. E Hoe/finer. BYW

T'OENE 715 Dec. 8, 1925. v 1,565,015

L. F. KOELLNER INTERNAL MANDREL FOR EEADERS Filed March 21, 1924 4 Sheets-Sheet 3 Dec. 1925- L. F. KOELLNER INTERNAL "ANDREI: FOR HEADERS Filed March 21, 1924 4 Shegts-Sheet 4 [HE Kae/fiver. BYWM ENEYj Patented Dec. 8, 1925.

UNITED STATES mourn F. KOELLNEB, or s'r. toms,- ia ssoumlaasg e lm qi KE Q E 393 or sr. LOUIS, Mrssounr, A conrortaa ron orgvrrssounr,

INTERNAL meanest. 7 1a Application filed-March 21, 1923;. Serial 1%. W034i;

To all whom itv may concern..-

Be it known that I, Lo'Urn FL KOELLN R, a citizen of the United States, re'sid'ingat' St. Louis, Missouri, have invented a certain new and useful Improvement in Internal Mandre'ls for Headers, of which the followingis' a full", clear and eXactde'sjcr-iption,

such as will enable others skilled in the art to which it appertains to make and use the same. v

I This invention relates to sectional headers for boilers or similar structures of the. general type disclosed in the pendin applicatio'nsfor patent of Alfred (lotton 'erial No. 596,432, filed October 23, 1922 and Serial No. 655,667, filed August 4 1923'.

The header described in the said Got-ton applications is distinguished from the coir ventional serpentine boiler header principally by reason of the fact that' it is con struoted from a tube which is deformed :by pressure applied externally to the tube in four different directions and inpsuch a way as to press opposed portions of the tube inwardly and cause opposed portions of the tube to bulge outwardly, thereby producing a header whose lateral sides are made up of diametrically-opposed ridges and diametrically-opposed valleys arranged in alternate relation and whose front and rear sides are also made up of ridges and valleys arranged in alternate relation with each other and in staggered relation with the ridges and valleys on the lateral sides of the header. In manufacturing such a header the tube from which it is constructed can be deformed by. a single operation or a continuous operation so as to producea header hav ing bulged portions of the kind mentioned and flat surfaces on its front and rear sides that constitute seats forthe' hand hole covers of the header and the boiler tubes which are connected to the header, or saidtubecan be deformed by one operation-that produces-the inwardly-pressed portions, the outwardlybulged portions and partially formed seats, and thereafter subjected to a second operation wherein the seats are completed or finished in such a way that they will be" of the required area.

My invention consists of a mandrel for internally supporting certain portions of a tube that i.-""i.19ll1g deformed to produce a header of'the -generah desigmdisclosed inthe said Cotton:"ap lications',gami ada tedthe header at the completion .ofthe de forming or shaping operation.

Another ob'ect is to prov-idea mandrel for the purpose describedwhich is of sucha design that it can be modified easily to adapt it to the manufacture of headers iof different lengths and headers .ha-Vingiend portions of different shapes and dimensions.

To this end I have devised an internal mandrel that is composed. of a number-of pairs of members arranged .en d -.\to.; end, lengthwise of the mandrel, and eachimember provided with a die element/that is adapted to co-operate wlhh aflfli externalsidie to form a flat surface on the 'i-1'1I161" .SlCle of the tube being deformed, said fiat facebeing. adapted to be used as a seat for a large tube or hand hole coveror'for a plural: ity of small tubes or hand hole covers; When the mandrel is in use. the various pairs of members that .constituteuthe com-. p'lete ma-n drel are held securely clamped together by pressure that is exerted .onsa'id pairs of members in a direction longitudinally of the header, and the two members that constitute each of said pairs are .of

such shape that one co-operates with the other to take-up or resist the inward thrusts of the external dies, namely, the: thrusts at right angles to the longitudinal axis of the mandrel. In order that-the mandrel may be used successfully with a tube or header that isdeformed or shaped while it is in a heated condition, I construct the mandrel in such a way thatshrinkage' of the tube or header, cause-d by the cooling of themetal of which-it is constructed, will not result in the members constituting the mandrel being gripped by the tube or header in; such a way as to interfere withtheieasy removal of said members. Tofit hisyendxl' provideethe two members of -each ofsaidpairsaivitlrop positely-inclined surfaces that bear against each other during the deforming operation, thus causing one member to support the other, and which are of such angularity that if the endwise pressure on the pairs. of members is relieved at the completion of the deforming operation, longitudinal or diametral shrinkage of the tube or header when it starts to cool will cause the two members constituting each pair to move inwardly towards the longitudinal axis of the mandrel, thus partially collapsing the ma drel or reducing the transverse dimensions of same sufficiently to prevent the mandrel from being gripped tightly by the tube or header when it contracts.

In the form of my invention herein illustrated the various pairs of members that make up the complete mandrel are held securelyclamped together by an element that extends longitudinally of the mandrel, and said pairs of members are provided with co-operating surfaces dispose? at right angles to said longitudinal-ll-disposed retaining element so as to cause each pair of members to bear evenly on the adjacent pair or on the two pairs of members between which it is arranged, when said. retaining element is adjusted to clamp the pairs of members together. It is preferable to construct said members in such a way that it is not necessary to thread the longitudinally-disposed retaining element through holes in said members of the same diameter as the retaining element, as such design enables the co-operating parts of the mandrel to be assembled and disassembled quickly and easily. With such a design, however, it

is advisable to provide the two members of each pair of members with cooperating means for maintaining said members in the same plane and also provide the various pairs of members with co-operating means for preventing the adjacent pairs of members from moving out of alignment with each'other. Due to the fact that the die elements on the mandrel and the external die that co-operate with said die elements are of such shape that the pressure which the external dies exert on the mandrel during the deforming operation tends to force the members at one side of the center axis of the mandrel longitudinally in one direc tion and force the members at the other side of the center axis of the mandrel longitudinally in the oppoiste direction, I an range the members so that one member of each pair is disposed in diagonal relationship with a member of an adjacent pair and with co-operating surfaces on said diagonally-disposed members bearing against each other in such a way that the endwise thrusts exerted by the external die on the members at the right hand side of the longitudinal axis of the mandrel are balanced by the endwise thrusts exerted by the opposed external die on the members at the left hand side of the longitudinal axis of the mandrel, thereby preventing the two members constituting each pair of members from moving longitudinally of the mandrel in opposite directions.

Figure 1 of the drawings is a side elevational view of my improved mandrel, showing the pairs of members constituting the mandrel clamped together in operative position.

Figure 2 is a said mandrel.

Figure 3 is a side elevational view of a portion of the mandrel, showing it arranged inside of a tube that is to be pressed or deformed, so as to produce a sectional header of the kind disclosed in the said Gotton applications. 7

Figure 4C is a view, illustrating the action of the front and rear dies on the tube inside of which the mandrel is arranged, the mandrel and external dies being shown in side elevation and the tube in longitudinal section.

Figure 5 is a view, illustrating the operation of removing the mandrel members from the header at the completion of the deforming operation.

Figure 6 is a perspective view of one of the mandrel members.

Figure 7 is a perspective view, showing how the header looks at the completion of the deforming operation.

Figures 8 and 9 are a side elevational view and a rear elevational view of a mandrel of slightly different construction from the one shown in Figures 1 and 2.

Figure 10 is a perspective view of one of the members of the mandrel shown in Figures 8 and 9.

Figure 11 is atop plan view of the apparatus that is used in the operation of assembling the members that constitute the mandrel; and

Figure 12 is a side elevational view of said apparatus.

Referring to Figures 1 to 7 of the drawings which illustrate the preferred form of my invention, A and A designate a plurali-ty of members that are combined in such a way as to form a mandrel which is adapted to be arranged inside of a tube a during the operation of deforming said tube so as to produce a sectional header of the kind shown in Figure 7 having lateral sides made up of diametrically-opposed ridges 1 and diametrically-opposed valleys 2 arranged in alternate relation, and front and rear sides made up of transverse ridges 1 and valleys 2 arranged in alternate relation with each other and in staggered relation with the ridges and valleys in the lateral sides of the header. Said mandrel .is provided with rear elevational view of it is provided onits front and rear sideswith groups of relatively'wide die elements and groups of relatively narrow die ele ments arranged in alternate relation and equipped with inclined faces that co-operate with the external dies to form groups of wide and narrow flat surfaces and 2 on the front and rear sides of the header, as

shown in Figure 7, that are inclined slightly *with relation to the longitudinal axis of the header, as shown more clearly in Figure '4. The wide and narrow flat surfaces 3/ and .2 on the rear side of the header are adapted to have holes formed in same for receiving the tubes to which the header is to be con nected', and the wide and narrow surfaces 3/ and z on'the front side of=the header are adapted to have hand holes formed in same. Therefore, it is necessary that the wide and narrow portions y and z in the front and rear sides of the header have sharp angles and flat inner faces disposed at right angles to the longitudinal axis of the tubes so as to form seats forthe tubes and seats for the gaskets that are used with the hand hole covers. Said mandrel is not restricted to use with any particular type or kind of external dies and the shape, form and arrangement of the die elements of the mandrel can be varied greatly without departing from the spirit of my invention. In manufacturing a sectional header of the kind disclosed in the said Cotton applications it is not necessary to internally support the portions of the tube on which the lateral side dies act, and therefore, I have only illustrated the front and rear external dies that co-operate with the mandrel to produce the flat hand hole cover seats and tube seats in the front and rear sides of the header. Moreover, while I have shown the front and rear external dies as consisting of two opposed, verfi ally-disposed dies that move horizontally towards and away" from the longitudinal axis of the mandrel while the mandrel is stationarily supported, I do not wish it to be understood that the mandrel is limited to use with a'deforming apparatus of this particular type or kind.

As previously stated, my improved mandrel is made up of a number of members A and A. Said members are arranged in pairs with the pairs disposed in superinn posed relation, as shown in Figures land 2,

arranged in an upright position'in the press, H

a heated tube as is then slipped over the mandrel endwise, as shown in Figure 3, and thereafter, the external dies B and B are moved inwardly towards the longitudinal axis of the mandrel so as to press the tube 00 into the shape shown in Figure 4:. At the completion of the deforming operation the external dies are separated or moved outwardly and the endwise pressure on the mandrel mem ersA and A is relieved so as to permit the mandrel members to auto matically move into such positions that they will not be gripped tightly by the header when it shrinks, due to the cooling-of the metal of which it is constructed. Thereafter, the mandrel and the header inside of which it isarranged are removed a single unit from the press.

Various means can beused'for exerting endwise pressure on the mandrel members A and A, so, as to clamp the pairs of members together, but I prefer to use along rod or bolt 0 that extends longitudinally of the mandrel and which is provided at one end witha nutor equivalent element C that is adapted to be turned inonedirection to securely clamp the pairs of members A and A together, and turned in the opposite directionsoxas to relievev theendwise pressure on said pairs of members. Preferably, the members A and A are -.con-

structedin'such a way that itis not necessaryto thread the retaining elementxC'through small holes in said members. In the form oflmy invention herein illustrated each of the members Aand A consists of a cast metal block provided with two sidewalls 3 and a connecting wall 4 :disposed at ,sub-

stantially right angles to each other, as shown in Figure 6, thus forming a practical ly hollow member that is open atits -inner side. The walla is provided with ,ani-nte gral die'element 5 that projects outw and the side walls 3 are providedwith' inclined surfaces 6. As shown inFigure 1,

the inclined surfaces 6 on the members -A are disposed oppositely .to' the inclined surfaces 6of the members A so as to causethe two members constituting each of said-pairs to back up each other to resist the inward thrusts of the external dies Band B. In other words, when the, members .A and A constituting the mandrelare assembled and clamped tightly together, the two members A and A constituting each pair co-operate rith each other to form a; practicallynsolid or rigid internal die that internally supports the opposed portions of the tube .00 that are being pressed inwardly by the co-operating portions of the front and rear dies B and B. At the completion of the deforming operation, after the adjustable device 0- on the retaining element C has been backed off or loosened so as to relieve the endWise pressure on the pairs of members A and A, the inclined surface 6 of one member of each pair is free to slide over the inclined surface 6 of the member with which it co-operates when the header shrinks, due to the cooling of the metal of which it is constructed, thereby causing the mandrel to collapse sufficiently to prevent it from being gripped tightly by the header, but not sufficiently to completely disengage it from the head r. The inclined portions 6 of the members A and A are preferably machined surfaces, and While the angle of said surfaces can be varied greatly, I have found that if the angle of the surfaces 6, with respect to the face of the die element 5, is made approximately 20 degrees, that the co-operating members of the various pairs will mutually support each other during the deforming operation and will be capable of moving relatively to each other sufficiently, after the clamping device C has been loosened, to eliminate the possibility of the mandrel being gripped tightly by the header when it shrinks. The various pairs of members A and A that make up the complete mandrel are provided with cooperating surfaces disposed at substantially right angles to the retaining elementC, that bear against each other when the nut C on said retaining element is tightened. These surfaces may be comparatively small in area, because they do not sustain any of the compressive force utilized to deform the header, and in the form of my invention herein illustrated each of the mandrel memhers is provided at its upper and lower ends with two bearing surfaces, designated by the reference characters 7 and 7*, formed preferably by the upper and lower ends of the connecting walls l of the mandrel member. As these surfaces 7 and 7 are disposed at right angles to the retaining element 0,, the operation of tightening the adjustable device C on the retaining ele ment C causes all of the mandrel members at one side of the center axis of the mandrel to be clamped tightly together and causes all of the mandrel members at the other side of the center axis of the mandrel tobe clamped tightly together. 6

Owing to the fact that the main function of the retaining'element C'and its co-operating adjustable device C is to exert endwise pressure on the pairs of members A and A so as to clamp them together, it is desirable to provide means for maintaining the pairs of'members in longitudinal alignment with each other and to prevent the member A of each pair from moving transversely with relation to its co-operating member A in a direction to disengage the co-operating inclined surfaces 6 on said members or destroy the alignment of the die elements on said members with the external dies. There fore, I prefer to provide the connecting wall 4; of each mandrel member with a recess 8 and a projection 9, located at opposite ends of said wall, as shown in Figure 6, so that when the various members A and A are clamped together, as shown in Figure 1, the two members constituting each pair will be interlocked with an adjacent pair of members, or with the two pairs of members between which it is interposed. I also prefer to form the co-operating inclined surfaces 6 of each pair of members in such a way that they will interlock, which effect can be obtained by providing the inclined surface 6 of the member of one pair with a projection that fits in a depression or recess formed in the inclined surface of the co-operating member of the pair and designated by the reference character 10 in Figure 6. When the mandrel members are constructed in this way, the co-operating recess and projection on the inclined surfaces of the two members of each pair holds said members in alignment with each other and the co-operating recesses and projections 8 and 9 on the various pairs of members prevent said pairs from moving transversely out of longitudinal alignment with each other. I

By referring to Figures 4 and 5 it will be noted that when the front and rear dies move inwardly to squeeze the tube against the mandrel and press it into the die elements 5 on the mandrel, there is a force tending to raise the mandrel members arranged at one side of the center axis of the mandrel and depress the mandrel members arranged at the opposite side of the center axis of the mandrel. This is partly due to the resistance of the metal of the tube to sharp bending and partly to the direct horizontal pressure of the dies tending to cause the members A and A constituting each pair to slide along the inclined surfaces 6 on said members. In order to counteract this force I construct the mandrel members in such a way that one 1 member of each pair co-operates with a diagonally-disposed member of an adjacent pair to counteract the endwise thrusts exerted on the mandrel members in directions tending to move the two members constituting a pair longitudinally in opposite directions. In other words, in my improved mandrel the members constituting the mandrel are of such construction and arrangement that the longitudinal thrust exerted on the members at one side of the center axis of the mandrel is balanced by the opposed longitudinal thrust exerted on the members at the other side of the center axis of the mandrel, thereby overcoming any Ill) . members A is provided adjacent its upper end with surfaces 11, formed by inclined portions at the upper end of the side walls 3 of said member, that bear against 00 0p erating surfaces 12 on the lower end portion of the side walls of the diagonally-disposed member A." of the pair arranged immediately above the same. Consequently, the up ward thrust that is exerted-on the members A of the mandrel by the frontdie B during the deforming operation is counteracted by the down Ward thrustthat is. exerted on the members A of the mandrel by the rear die B. These co-op'erating surfaces 11' and 12 are preferably disposed at a considerable angle to the horizontal so as to permit of a, relatively great longitudinal movement of the members A with relation to the members A after the en'dwise pressure on the various pairs of mandrel'members has been relieved tion. It is not absolutely essential that the co-operating surfaces 11 and 12 of the mandrel members be inclined, for it is feasible to equip the members A and A of the man drel with horizontally-disposed co-operating surfaces 11 and 12, as shown in Figures 8, 9 and 10, for counteracting the opposed longitudinal thrusts on the mandrel members do ing the deformingoperation. However, when the mandrel members are provided with co-operating'inclined surfaces 11 and 1-2, as in the form of my invention illustrated in Figures 1 to 6, inclusive, a slight slackening of the clamping device C on the retaininge-lement C at thecompletion of the deforming operation permits the diagonallyopposed members of the mandrel to move a great distance relatively to each other, and thus eliminate the possibility of the mandrel members being gripped by aXi-al or longitudinal shrinkage of the header. Another advantage that results from providing the mandrel members with inclined co-operating surfaces 11 and 12 of the kind mentionedlis that the members A at the right hand side of the center axis of the mandrel" are inter' locked with the members A atthe left hand side of the center axis of the mandrel in such a way that the members of the respective pairs are prevented from movingoutwardly away from each other. "Consequently, the co-operati-ng surfaces 11 and 12 on the mandrel members not only ca usethe' diagonally-- disposed members to "co-operate with each.

other to balance the opposed endwise thrusts exerted on the mandrel members by the pressing dies, but they also prevent the cooperating members of the respectiveipairs fron mo goutwardly away from the Gen.- teraziisa ofthe mandrel. 'The'two pairs of members A and A" at the'opposite ends of the mandrel are provided with dis elements 5* thatco-operate with the external dies to shape the end portions of the 'header,- and' the mandrel is, provid'edyat its 1 lower end with a bas iecell that is adapted'torest upon a rat or othersupporting structure 14. which or. tains the mandrel. In the form of n'ry invention herein illustrated the base piece l-t provided with groove 15 for receiving a bar or other similar device 16, shown in Figure 4, that is used-to center the mandrel. The base piece'14 is also provided with locating plates: l7 on whichthe tube :17

operation. To facilitate accurately centering the tube relativelyfto the mandrel the locating plates 17 are provided with; sloping surfaces thaticause the tube to beautomatically centered'with relation to the longitudinal axis of the mandrel when thetube is slipped down over the mandrel during the operation of. arranging the tube in the I w 7 press. I at the completion of the deforming opera- In usi-ngmy improved mandrel to produce a header ofthe kind shownin Figure 7, the

mandrel is first arrangedrin an uprightposi- 'tlonin the press betweenthe front and rear dies B and B" and a heated tube as is then lowered into position surrounding'the "mandrel and: resting centrally'upon the locating plateslZ. The press isthen set'in operation so as-to cause the external-dies to move I inwardly into engagement with the tube, thus" causing the front and rear dies to cooperate with the die elementsfi on the-man- 1 6 on the. said members, and thus elongate the mandrel as a Whole, but this tendency; of the mandrelunember's to slide'is'prevented by the retaining element which exerts endwise pressure on the pairs of mandrel members to 110101 the. co-operating surfaces 7 and "7 of said members pressed tightly together.

After the. tube has been:'deform'ed by the inward. movement of the eX'ter-nal'dies the nut C. atthe upper end of;theretainingelement C is loosened or backed 'fofi' slightly so as to relieve the end-wiselpress ure on the pairs of members A and A that make up themandrel, and; thus. permit the two opposed members;-I of each pair to move: in- I is positioned preparatory to: the deforming Wardly and also longitudinally suflici'ent'lyf to' prevent said membersfrom being" to 'the'co'oling "of the metal of whichfitgis in d tightly by'thefheader when itishrin s', ue

are then lifted as a single unit out of the press and laid on a table or other supporting structure while the retaining element 0 and mandrel members A and A are withdrawn from the header, as shown in Figure 5.

In assembling the parts of the mandrel 1t is preferable to use an assembling apparatus of the kind shown in Figures 11 and 12, which is composed of a hinged or pivotallymountedtable 18 that is adapted to be arranged in a horizontal position, as shown in Figure 12, during the assembling operation, and which is provided on its top side with a plurality of locating brackets 19. The mandrel members A and A are arranged fiatwise on the table 18 with the fiat face of the die elements 5 on said members bearing against the locating brackets on the table, as shown in broken lines in Figure 11, and after the mandrel members have been assembled the retaining element C is moved longitudinally through the same and the nut C is screwed onto the end of the element C so as to clamp the members together. The table 18 is then swung into and upright position, as shown in broken lines in Figure 12, and a crane hook is then inserted in the ring 20 on the nut'C of the retaining element and the mandrel thereafter removed to the press where it'is to be used or to the point where it is to be stored.

A mandrel of the construction above described can be assembled and disassembled quickly and easily, as it is composed of a plurality of pairs of members that are combined in such a way that they readily fall apart as soon as the nut C of the retaining element C is removed. Such a mandrel can be modified easily to adapt it to the manufacture of headers of various lengths and headers having end portions of different shapes and dimensions, and as it is composed principally of cast metal members, it is strong and rugged enough to successfully withstand rough handling. In addition to the desirable features above pointed out, my improved mandrel is of such design that there is no liability of its being gripped tightly by the header when it shrinks or contracts, because the members constituting the mandrel are so constructed and combined that a slight slackening or backing off the nut C of the retaining element permits the mandrel members to move inwardly, thus allowing for diametral shrinkage and also move lengthwise of the mandrel, thus allowing for longitudinal shrinkage of the header. 7

Having thus described my invention, what 'I claim as new and desire to secure by Letters Patent is: V 1. An internal mandrel that is adapted to bearrangedinside of a tube that is being fdeformed to produce a header, saidmandrel being composed ofa plurality of pairs of separable members arranged end to end and provided with die elements that are adapted to co-operate with external dies to form flat seat faces on the front and rear sides of the header, and means for holding said members immovable or in rigid relation with each other during the deforming operation.

' 2. An internal mandrel for the purpose described, composed of a plurality of pairs of separable members arranged end to end and each provided with a die element that is adapted to co-operate with an external die to form a fiat seat face on a tube inside of which the mandrel is arranged, and means for exerting endwise pressure on said members and maintaining them in rigid relationship with each other during the operation of deforming the tube. V

3. An internal mandrel for the purpose described, composed of a plurality of pairs of separable members arranged end to end and each provided with a die element that is adapted to co-operate with an external die to form a flat seat face on a tube inside of which the mandrel is arranged, means for exerting endwise pressure on said members to maintain said pairs in operative relationship with each other, and co-operating inclined surfaces on the members of each pair disposed so that said members are capable of moving slightly relatively to each other after the endwise pressure on said members has been relieved. V

4. An internal mandrel for the purpose described, composed of a plurality of memlOU bers arranged end to end and provided with die elements that are adapted to co-operate with external dies which act on the tube inside of which the mandrel is arranged, means for exerting pressure on said members longitudinally of the mandrel, cooperating surfaces on said members dis posed so as to cause said pairs of members to be clamped together by said pressure, and co-operating inclined surfaces on the two members constituting each pair disposed so that one member backs up the other to resist the inward force of the external dies during the deforming operation but the co-operating members of the respective pairs are capable of rmoving inwardly towards the longitudinal axis of the mandrel after the longitudinal pressure on the pairs of members has been relieved.

5. An internal mandrel for the purpose described, composed of a plurality of pairs of members arranged end to end and provided with die elements that are adapted to co-operate with external dies which act on the tube inside of which the mandrelis arranged, means for exerting sufficient endwise pressure on said pairs of members to hold them immovable or in rigid relationship with each other during the deforming operation, and means for-holding the two members constitiiti ng each of said pairs in vided with die elements that; are adapted to comperate with external di'es which act on the tube inside of which the mandrel is arranged, means for holding said members in rigid relation with each other during 'the deforming operation, and an independent means for maintaining the respective pairs of members in longitudinal alignment with each other. I 7, internal mandrel for the pur ose described, composed of a plnrality of pairs of V members arranged end to end and rovid'e'd with (He elements that are adapted to co-operate with external dies Which act on the tube inside of which tliein'andr'el is arranged, means for exerting jendwise pres sure on said pairs of m'e'mbersin such as to hold, them immovable or inrigi'd' rela3 tion with each other during the deforming operation,-m'eans for maintaining the membersof each pair in alignment with each other, and an independent means for maintainingthe respective pairs." of members in longitudinal alignment, I I

I 8. An internal mandrel for the purpose described, compesed "of a plurality 'ofpairs of members arranged end toen'd and'each provided with a die elementthatis'adapte'd to co-operate with an external di'e'that acts on the tube inside of which the mandrel is I arranged, m ansjor holding said members in rigid relationship with each other during the I deforming 'oper'atien, and cooperating surfaces on 'saidmahdrel members disposed so that longitudinal thrusts exerted on the members at one ide of the center axis or the mandrel tending "to move said members in one direction coi'intera'cts thrusts exerted on the members at the 'other'fside or the center axis of't'he m n'drel reading toinov'e said members longitudinally intne o posite direction.

9. A mandrel for tire purpose (ilesci ibe'd, composed prpairsof in'enib'ers arranged end to end, means for exerting endwis'e pressure 'on said members to hold them immovable dnri the deforming operation and co-opei-anng surfaces on said mandrel members for counteracting thrusts exerted on said members by the external dies in directions tending to force the members of each pair longitudinally in opposite directions.

10. An internal mandrel composed of a plurality of pairs of members arranged end to end and each provided with a die element that is adapted to co-operate with an external die which acts on the tube inside of which the mandrel is arranged, means for preventing said members from moving relatively to each otherduring the deforming operation, and (Bo-operating interlockiii-9" portions on the 'invoniernbers of earth of 's'aid pairs; 7 7

p Q. An internal mandrel composed ofa pliirality of pairs Diff-members arranged end to end and provided with die elements that are. adapted to co-operatewith an external die which acts on the tube inside of Whichthe inan'dr'el is arranged, means for lielding said members "immovable or in rigid relation with each otheifchiring the deforming operation, and 'oompera'ting inter locking. portion's on the respective pairs of members.

12. An internal n'iandrel composed offa pluralityof pairs of members arranged end to end and provided 'wit'li'die" elemen'ts that are adapted to cuppa-ate. with anext'ernal die ii 'hi'clji acts on the tube inside offwhich' the mandrel is arranged,}n1 eans for hold ing said members in rigid relationship'with each ther during the deforming "o 'qeration, interlocking portions on the two members constituting each of said pairs, and interlocking portions on the respective pairs of members. i

13. internal niandi' el for the purpose I deseribe'd; composed of'fa' plurality of pairs of members arranged end toend 'an'dpr'og vided' with die elements that are adapted to co-oper-ate with the external-"dies that act -onthe tube insideof which the mandrel is I arranged, the two members constituting each of said-pairs beingprovided withgo'p .positely-inclined surfaces t'h'at bear against each other during "the: deformingoperation, means for exerting endwilse pressureon the pairs of members to clamp them together,

and means for maintaining the two members constituting each oi. said ai'rs in alignment with each oth r and, for-maintainin the respective pairs of members "in longitudinal alignment when the endwi'se pressure" on said pairs of members is relieved at the completion of the deforming-oper ation. e n I 7 14. An internal mandrel for-the purpose described, composed. of: aplural'ifiy of. pairs or members-arranged end to-end andea'ch provided with a die element that is. adaptedto co-operate with an external die that acts on the tubeinside ofwhich the mandrel is arranged, said pairs of members" being so constructed and combined that one member of each pair is disposed in diagonal relationship with the opposite member of an adjacent pair and with co-operating surfaces on said diagonally-disposed members bearing against each other, and means for,

holding said members immovable or in rigid relation with each other during the deforming operation a 15; An internal .m'andrel for thepurpose described, composed of a plurality of pairs of members arrangedend to end, co-operaL pressure on said members,

ing inclined surfaces on the two members of each pair, means for exerting endwise pressure on said pairs of members to hold them in rigid relation with each other during the deforming operation, said means be- 'ing adapted to be manipulated at the completion of the deforming operation so as to relieve the end pressure on said pairs of members and permit the mandrel to collapse sufficiently to provide for the shrinkage of the header inside-of which it is arranged, and co-operating interlocking portions on sai said members from moving outwardly away from the center axis of the mandrel.

16. An internal mandrel for the purpose described, composed of a plurality of pairs of members arranged end to end and each provided with a die element that is adapted to co-operate with an external die which acts on the tube inside of which the mandrel is arranged, means that is adapted to be manipulated to clamp said pairs of members together during the deforming operation and to, thereafter relieve the endwise and co-operating surfaces on the pairs of members disposed so as to permit of. a relatively great diagonal movement of'said members without collapsing the mandrel to such an extent as to disengage it from the header,

17. An internal mandrel for the purpose described, composed of a plurality of members arranged end to end and each provided with a die element that is adapted to cooperate with'an external die that acts on the tube inside of which the mandrel is arranged, a retaining element arranged longitudinally of said members for exerting endwise pressure on same to clamp them together, co-operating inclined surfaces on the two members of each of said pairs, and independent co-operating surfaces on the members of the respective pairs disposed at substantially right angles to said retaining element.

18. An internal mandrel for the purpose described, composed of a plurality of members arranged end to end and each provided with a die element that is adapted to cooperate with an external die that acts on the'tube inside of which the mandrel is arranged, a retaining element arranged l pairs of members that prevent longitudinally of said members for exerting endwise pressure on same to clamp them together, co-operating inclined surfaces on the two members of each of said pairs, independent co-operating surfaces on the members of the respective pairs disposed at substantially right angles to said retaining element, co-opcrating interlocking portions on the inclined surfaces of said members, and co-operating interlocking portions on the respective pairs of members. i

19. An internal mandrel for the purpose described, composed of a plurality of pairs of members arranged end to end, means for holding said members in rigid relationship with each other during the deforming operation and means at one end of the mandrel for centering a tube that is slipped over the manerel. v

20. An internal mandrel for the purpose described, composed of a plurality of pairs of members arrangedend to end with the two members of each pair disposed oppositely to each other and the opposite members of adjacent pairs in diagonal relationship, a die element on each of said members, a retaining element arranged longitudinally of the mandrel for exerting endwise pressure on the pairs of members during the deforming operation and provided with an adjustable element that is adapted to be manipulated to relieve said endwise pressure at the completion of the deforming operation, (o-operating inclined surfaces on the two members of each pair disposed so as to permit said members to move inwardly towards the longitudinal axis of the mandrel and thus allow unrestricted shrinkage of the header inside of which the mandrel is ar ranged, co-operating surfaces on therespective pairs of members disposed at substan tially right angles to said retaining element, and co-operating surfaces on the diagonallydi'sposed members that prevent movement of said members away from the longitudinal axis of the header, prevent the two members of each pair from moving longitudinally in opposite directions and which allow considerable diagonal movement of the various members constituting the mandrel when the endwise pressure on said members is relieved.

' LOUIE F. KOELLNER. 

